1. Field of the Invention
The present invention relates to a pulse wave monitoring device for monitoring a pulse wave of an organism and, more particularly, to a pulse wave monitoring device for supporting a diagnosis.
2. Description of the Related Art
In close examinations for diagnosing cardio vascular diseases such as hypertension, anbulatory blood pressure monitoring, echocardiography using an ultrasonic diagnostic unit, eyegrounds test, electrocardiography, exercise tolerance test, and the like are conducted. The blood pressure measurement is, however, conducted the most widely as the examinations including the close examinations to general diagnosis. This is because the blood pressure measurement has excellent characteristics such that it can be conducted simply in a noninvasive manner and a measuring device is more inexpensive than devices for another examinations.
Since information obtained form the blood pressure measurement, however, includes only information about whether a blood pressure is at a notable level, the blood pressure measurement judges whether an examinee is a hypertensive patient. A doctor should overall determine, however, how to cure a disease based on information obtained from another examined results and inquiry. The information obtained from the inquiry occasionally includes patient's subjective information, and this occasionally causes misdiagnosis.
In order to conduct more excellent diagnoses of cardio vascular diseases, it is desired, therefore, to provide objective information which supports diagnosis of hypertension and determination of a curing way to doctors without deteriorating the excellent characteristics of the blood pressure measurement.
In order to respond such a request, different two physiologic indices (an adjusted pulse wave velocity and blood pressure index of ankle/upper arm) are expressed by a two-dimensional graph, so that a state transition of a patient can be easily known (see, for example, Specification and Drawings of Japanese Patent Application Laid-Open No. 2000-316821).
Further in order to easily understand the patient's state, a device, that expresses the different two physiologic indices (diastolis pressure and classified results of waveforms of acceleration plethysmogram obtained by a pulse wave pattern classifying unit) using a two-dimensional graph, is also suggested (for example, Specification and Drawings of Japanese Patent Application Laid-Open No. 2000-217796).
Further, a device, that expresses the two kinds of the physiologic indices using the two-dimensional graph and displays a circulating state of a patient, is also suggested (for example, Specification and Drawings of Japanese Patent Application Laid-Open No. 11-332837 (1999)). As a combination of the two physiologic indices includes: a combination 1 of systole time and pulse rate variability; a combination 2 of systole time and blood pressure; a combination 3 of classification of the waveform of the acceleration plethysmogram by the pulse wave pattern classifying unit and blood pressure; a combination 4 of pule wave propagating time; and a combination 5 of systole time and arteriosclerosis.
In the device in Japanese Patent Application Laid-Open No. 2000-316821, however, pulse waves and blood pressure at two points separated from each other should be measured in the measurement of an adjusted pulse wave velocity and an blood pressure index of an ankle/an upper arm. For this reason, the measurement is complicated and cannot be conducted simply.
In the device of Japanese Patent Application Laid-Open No. 2000-217796, since a correlation between the classified result of the waveform of the acceleration plethysmogram by the pulse wave pattern classifying unit and the other physiologic indices is not clear, the classified result is not generally used for clinical diagnoses. Further, as explained in embodiments, the waveform of the acceleration plethysmogram is classified mostly on a tip of finger by the pulse wave pattern classifying unit. Since the tip of finger is, however, easily influenced by environmental temperature, mental stress and the like, it is difficult to collect plethysmogram with stability and reproducibility. For this reason, the result of classifying the acceleration plethysmogram by the pulse wave pattern classifying unit is unstable and has insufficient reproducibility, and the use of the classified result possibly causes misdiagnosis.
In the embodiments, a tip of finger pulse wave is monitored by photo electric plethysmogram pulse wave. The photo electric plethysmogram pulse wave shows a waveform which is deformed by nonlinearity between intravascular pressure and vascular capacity. An compositive element is mixed in the result of classifying the waveform of the acceleration plethysmogram in the photo electric plethysmogram by the pulse wave pattern classifying unit, and physiologic meaning of this result become unclear.
The combinations 3 and 5 in the device of the Japanese Patent Application Laid-Open No. 11-332837 (1999) have the same problem as that in the device of the Japanese Patent Application Laid-Open No. 2000-217796, and the combination 4 has the same problem as that in Japanese Patent Application Laid-Open No. 2000-316821. Since the combinations 1, 2 and 4 do not use characteristic parameters of the pulse wave, a diagnosis cannot be supported by presenting the characteristic parameters obtained based on the pulse wave.